In₂S₃/MXene‐Gated Organic Photoelectrochemical Transistor With Target‐Induced Dipedal DNA Walker Modulation for DBP Biosensing

Abstract Organic photoelectrochemical transistor (OPECT) biosensor have become an advanced bioanalytical technology due to their superior performance. In this work, a novel target‐induced bipedal DNA walker‐mediated and In₂S₃/Ti₃C₂ (MXene) Schottky junction‐gated OPECT aptasensor is developed. The DNA walker is activated by recognition between the aptamer and the target, and then moved along a predetermined orbital interface, realizing the integration of target recognition and signal amplification detection, thus obtaining higher detection sensitivity and shorter detection duration. To validate the innovative nature of OPECT bioassays, signals are obtained on OPECT‐specific detection of dibutyl phthalate (DBP) as a target molecule through alkaline phosphatase ‐mediated ascorbic acid (AA) enrichment at the In₂S₃/MXene photosensitive gate. AA enrichment effectively depleted holes and enhanced the photoelectric response by inhibiting electron‐hole pair complexation, realizing effective modulation of the organic semiconductor poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate). The presented OPECT aptasensor achieved sensitive detection of DBP and provided a low detection limit of 0.18 fM based on the homogeneous, well‐integrated nature of aptamer recognition. Considering the detection of different toxicant molecules, it is expected to serve as a generalized tool with excellent performance.